Shims are used in many facets of assembly operations to position and fill residual gaps between assembled parts. The need for shimming is particularly acute in aerospace assembly operations due to the tight tolerance requirements and need to eliminate gaps at interfaces. Solid shims are, in some cases, made of the same material as the interfacing parts. Laminated peelable shims may be made of foil layers that can be removed one-by-one until a good fit is achieved. Curable shim materials may be particularly useful in filling irregular or tapered interfaces. A two-part liquid shim formulation has been described, for example, in US2010/0203249A1.